Diaphragm valve

ABSTRACT

Provided is a diaphragm valve that is capable of increasing its flow rate and is capable of suppressing variation among the diaphragm valves in the flow rates. In a diaphragm valve  1 , a fluid that has flown into the fluid inflow channel  2   a  enters a fluid outflow channel  2   b  via through holes  22   a  of a seat holder  5 . On a bottom surface  13  of a depression  2   c  of a body  2 , a seat receiving surface  13   a  that receives a seat  4  is flush with a seat-holder receiving surface  13   b  that receives a seat holder  5 . In the bottom surface of the depression  2   c  of the body  2 , an annular groove  14  facing through holes  22  of the seat holder  5  is formed.

TECHNICAL FIELD

The present invention relates to diaphragm valves, and more particularlyrelates to a diaphragm valve in which a seat is demountably held by aseat holder.

BACKGROUND ART

A conventionally known diaphragm valve includes: a body having a fluidinflow channel, a fluid outflow channel, and a depression openingupward; a seat demountably disposed on a circumferential edge of thefluid inflow channel of the body; a seat holder demountably disposed onthe body to hold the seat; a diaphragm that is pressed against andseparated from the seat to open and close the fluid channel; andvertically moving means for vertically moving a diaphragm presser thatpresses a central portion of the diaphragm (Patent Literature 1, etc.).

The seat holder includes a plurality of through holes that communicatewith the fluid outflow channel. In an open state in which the diaphragmis separated from the seat, a fluid that has flown into the fluid inflowchannel enters a space created between the diaphragm and the seat andthen flows into the fluid outflow channel through the through holescommunicating with the fluid outflow channel.

CITATION LIST Patent Literature

Patent Literature 1: JP-A-2013-117269

SUMMARY OF THE INVENTION Technical Problem

In the conventional diaphragm valve, one conceivable solution toincrease its flow rate is to increase diameters of: the fluid inflowchannel; the through holes of the seat holder; and the fluid outflowchannel. It is, however, difficult to increase the diameters of thefluid channels and the diameters of the through holes, without entailingincrease of the dimension of the body. So, increasing a flow rate of thediaphragm valve that uses a seat holder has been an issue to beachieved. In addition, when increasing the flow rate is attempted, aproblem arises in which products to be manufactured (diaphragm valves)are likely to have great variations in their flow rates, and suppressingthe variations is therefore also an issue to be achieved.

The purpose of the present invention is to provide a diaphragm valveboth capable of increasing the flow rate and capable of suppressingvariation in the flow rate among the diaphragm valves produced.

Solution to Problem

The diaphragm valve in accordance with the present invention is adiaphragm valve including: a body having a fluid inflow channel, a fluidoutflow channel, and a depression opening upward; a seat demountablydisposed on a circumferential edge of the fluid inflow channel of thebody; a seat holder demountably disposed on the body to hold the seat;and a diaphragm that is pressed against and separated from the seat toopen and close the fluid channel; the diaphragm valve in which a fluidthat has flown into the fluid inflow channel flows into the fluidoutflow channel via through holes formed in the seat holder, thediaphragm valve being characterized in that, on a bottom surface of thedepression of the body, a seat receiving surface to receive the seat anda seat-holder receiving surface to receive the seat holder are formedand that, in the bottom surface of the depression of the body, anannular groove that faces the through holes of the seat holder isformed.

This diaphragm valve is provided, on the bottom surface of thedepression of the body, with the seat receiving surface and theseat-holder receiving surface; and the diaphragm valve is capable ofincreasing the flow rate and is additionally capable of suppressingvariations in the flow rate among diaphragm valves produced, as comparedto a diaphragm valve having no annular groove in the bottom surface ofthe depression of the body.

The diaphragm valve may be a manual valve in which the vertically movingmeans is an opening and closing handle, or may be an automatic valve inwhich the vertically moving means is an adequate actuator. In the caseof the automatic valve, it may be operated by fluid (air)) pressure, ormay be operated by an electromagnetic force.

The seat holder is a known one and, for example, has the shape of a diskwith a hole at the center. The seat holder includes: an innercircumferential edge portion to hold the seat; an intermediate annularportion in which the plurality of through holes that communicate withthe fluid outflow channel are formed at predetermined intervals; and anouter circumferential edge portion that sandwiches an outercircumferential edge portion of the diaphragm.

It is preferable that the seat receiving surface is flush with theseat-holder receiving surface. It is also preferable that, among theseat receiving surface, the seat-holder receiving surface, and thebottom surface of the groove, the bottom surface of the groove is formedat a lowermost level.

It is preferable that the diaphragm valve further includes a retainerthat holds the seat holder. The retainer, for example, has asubstantially cylindrical shape and has an inward flange portion thatreceives the outer circumferential edge portion of the seat holder. Theflange portion, however, may take any shape as long as the retainer hasa structure such that the seat holder does not fall off from theretainer. The retainer may have a configuration of having a protrudingshape to hold the seat holder, instead of having the inward flangeportion.

The seat is preferably replaced when after having been used for a longperiod of time. Since the retainer that holds the seat holder isprovided, the seat holder held by the retainer and the seat held by theseat holder may be demounted by demounting the retainer, whereby theseat may be replaced easily.

Although the seat is formed of, for example, a synthetic resin, it maybe formed of metal as a matter of course. The seat holder and theretainer are preferably formed of metal.

The diaphragm is formed, for example, of a nickel alloy thin plate, andis formed into an inverted dish shape formed by being cut out into acircular shape and protruded at central portion thereof upward. Thediaphragm may be formed, for example, of a stainless steel thin plate,or a laminated body composed of a stainless steel thin plate and anickel-cobalt alloy thin plate. The material of the diaphragm is notspecifically limited thereto. In addition, the diaphragm may be a singlebody, or a laminated body composed of a plurality of diaphragms, and maybe selected freely depending on the specifications or conditions.

Advantageous Effects of Invention

With the diaphragm valve in accordance with the present invention, onthe bottom surface of the depression of the body, the seat receivingsurface that receives the seat and the seat-holder receiving surfacethat receives the seat holder are formed; and in the bottom surface ofthe depression of the body, the annular groove that faces the throughholes of the seat holder is formed. With this configuration, thediaphragm valve in accordance with the present invention is capable ofincreasing the flow rate and is capable of suppressing variations in theflow rates among the diaphragm valves, as compared to a diaphragm valvehaving only the seat receiving surface and the seat-holder receivingsurface on the bottom surface of the depression of the body and havingno annular groove in the bottom surface of the depression of the body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view showing one embodiment of adiaphragm valve in accordance with the present invention.

FIG. 2 is an enlarged view showing a seat holder that constitutes thediaphragm valve, in which (a) is a plan view, and (b) is a longitudinalsectional view.

FIG. 3 is a longitudinal sectional view showing a diaphragm valve, whichserves as a comparative example of the diaphragm valve in accordancewith the present invention.

REFERENCE SIGNS LIST

1: diaphragm valve, 2: body, 2 a: fluid inflow channel, 2 b: fluidoutflow channel, 2 c: depression, 4: seat, 5: seat holder, 6: diaphragm,13: bottom surface, 13 a: seat receiving surface, 13 b: seat-holderreceiving surface, 14: annular groove

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described with reference tothe drawings.

FIG. 1 shows one embodiment of the diaphragm valve in accordance withthe present invention. The diaphragm valve 1 includes: a block-like body2 having a fluid inflow channel 2 a, a fluid outflow channel 2 b, and adepression 2 c opening upward; a cylindrical hood 3 having a lower endportion screwed into an upper portion of the depression 2 c of the body2 and extending upward; an annular seat 4 disposed on a circumferentialedge of the fluid inflow channel 2 a; a seat holder 5 that is disposedon an outer circumference of the seat 4 within the body 2 and that holdsthe seat 4; a diaphragm 6 that is pressed against or separated from theseat 4 to open and close the fluid inflow channel 2 a; a stem 7 thathas, at an lower end thereof, a diaphragm presser 8 that presses acentral portion of the diaphragm 6, that is inserted within the hood 3in a vertically movable manner, and that causes the diaphragm 6 to pressagainst and separate from the seat 4 via the diaphragm presser 8; acompression coil spring (biasing member) 9 that biases the stem 7downward; a guide cylinder 10 that is disposed on an inner circumferenceof the hood 3, that guides vertical movement of the stem 7, and thatregulates a moving range of the stem 7; a diaphragm holding ring 11 thatis disposed between an upper surface of an outer circumferential edgeportion of the diaphragm 6 and a lower end of the guide cylinder 10, andthat holds the outer circumferential edge portion of the diaphragmbetween the diaphragm holding ring 11 and an outer circumferential edgeportion of the seat holder 5; a retainer 12 that holds the seat holder5, and that is mounted demountably on a lower end portion of the guidecylinder 10 and the diaphragm holding ring 11; and, vertically movingmeans (not shown) that causes the stem 7 and the diaphragm presser 8 tomove vertically with compressed air to open and close the fluid channel2 a.

The guide cylinder 10 includes a thick portion 10 a and a thin portion10 b continuing upward therefrom. The thick portion 10 a has an innercircumference that is larger in diameter than that of the thin portion10 b. The inner circumference of the thick portion 10 b guides an outercircumference of a flange portion of the stem 7. The thick portion 10 ahas an outer circumference that is larger in diameter than that of thethin portion 10 b. An upper surface (stepped surface between the thickportion 10 a and the thin portion 10 b) of the thick portion 10 areceives a lower end surface of the hood 3. Therefore, the hood 3 isscrewed into the body 2 whereby the guide cylinder 10 presses thediaphragm holding ring 11 downward. With this configuration, the guidecylinder 10 serves not only as a member for guiding the stem 7, but alsoas a member for fixing the diaphragm holding ring 11 to the body 2. Theguide cylinder 10 together with the diaphragm holding ring 11constitutes a diaphragm holding member that holds an outercircumferential edge portion of the diaphragm 6 between the combinationof the guide cylinder 10 together with the diaphragm holding ring 11,and the seat holder 5.

The seat holder 5 is made of metal and has the shape of a disk with ahole at the center. As shown in FIG. 2 in detail, the seat holder 5includes: an inner circumferential edge portion 21 that holds the seat4; an intermediate annular portion 22 in which a plurality of throughholes 22 a communicating with the fluid outflow channel 2 b are formedat predetermined intervals; and an outer circumferential edge portion 23that sandwiches the outer circumferential edge portion of the diaphragm6. A lower surface of the inner circumferential edge portion 21 is flushwith a lower surface of the outer circumferential edge portion 23. Anupper surface of the inner circumferential edge portion 21 is also flushwith an upper surface of the outer circumferential edge portion 23. Theseat 4 is fitted into the seat holder 5 from below.

In an open state in which the diaphragm 6 is separated from the seat 4,a fluid that has flown into the fluid inflow channel 2 a enters a spacecreated between the diaphragm 6 and the seat 4, and then flows into thefluid outflow channel 2 b through the through holes 22 a of the seatholder 5, which communicate with the fluid outflow channel 2 b.

To be in conformity to the configuration that the lower surface of theinner circumferential edge portion 21 of the seat holder 5 is flush withthe lower surface of the outer circumferential edge portion 23; on abottom surface 13 of the depression 2 c of the body 2, a seat receivingsurface 13 a that receives the seat 4 is flush with a seat-holderreceiving surface 13 b that receives the seat holder 5.

On the bottom surface 13 of the depression 2 c of the body 2, an annulargroove 14 facing the through holes 22 a of the seat holder 5 is formed.In FIG. 2, this annular groove 14 is shown by an alternate long and twoshort dashes line.

The lower surface of the inner circumferential edge portion 21 may notbe flush with the lower surface of the outer circumferential edgeportion 23. To be in conformity with the above configuration, the seatreceiving surface 13 a may not be flush with the seat-holder receivingsurface 13 b. That is, in a configuration that the seat receivingsurface 13 a, the seat-holder receiving surface 13 b, and the groove 14are adjacent to one another, it is sufficient if the groove 14 is formedbelow the through holes 22 a of the seat holder 5. So, among the seatreceiving surface 13 a, the seat-holder receiving surface 13 b, and thebottom surface of the groove 14, it is sufficient if the seat receivingsurface 13 a and the seat-holder receiving surface 13 b are formed to beon the higher level compared to that of the bottom surface of the groove14, since the bottom surface of the groove 14 needs to be at thelowermost level. In this case, one of the seat receiving surface 13 aand the seat-holder receiving surface 13 b may be at the higher levelcompared to the other.

The retainer 12, having a substantially cylindrical shape, includes: aperipheral wall 31 having an inner diameter substantially equal to theouter diameter of the seat 4 and fitted to the lower end portion of theguide cylinder 10 and the outer circumference of the diaphragm holdingring 11; and an inward flange portion provided at the lower end portionof the peripheral wall 31 and receiving the outer circumferential edgeportion of the seat holder 5. On the peripheral wall 31, four pairs ofslits (not shown) extending in the axial direction are provided forenabling easy deformation of the peripheral wall 31.

The seat 4 is held in the seat holder unit for a diaphragm valvecomposed of the seat holder 5 and the retainer 12, and is disposed inthe body 2. The seat 4 is configured normally to be replaced after beingused for a certain period of time. When the seat 4 is to be replaced,the seat holder 5 and the seat 4 held thereby may be demounted bydemounting the retainer 12. Subsequently, the seat 4 is replaced, andthe seat holder 5 is also replaced when needed, and then the seat holderunit for a diaphragm valve composed of the seat holder 5 and theretainer 12 is returned back to the interior of the body 2 in a state inwhich the seat 4 is held therein. In this manner, replacement of theseat 4 can be performed easily. The retainer 12 has little probabilityof being subjected to a plastic deformation, and hence can generally beused repeatedly. Moreover, because of the retainer having littleprobability of being subjected to a plastic deformation, easiness ofreplacement of the seat 4 can be maintained for a long period of time.

Table 1 shows results of measurement using a flowmeter with which flowrates of the diaphragm valves 1 described above were measured. Adiaphragm valve used as a Comparative Example in Table 1 is shown inFIG. 3. The diaphragm valve shown in FIG. 3 has no annular groove 14 inthe bottom surface 13 of the depression 2 c of the body, as compared tothe diaphragm valve 1 shown in FIG. 1. The flowmeter is a known one thatmeasures the flow rate of the sample products (in this case, diaphragmvalves) by providing nitrogen gas to the sample products at apredetermined pressure and flow rate, and the detailed description ofwhich is therefore omitted. Table 1 shows each value for the ten sampleproducts, the mean value, and the standard deviation. The unit of thevalues is NL/min.

TABLE 1 (Unit: NL/min.) Sample product Shape A Shape B 1 13.2 11.9 213.4 11.8 3 13.5 12 4 13.4 10.3 5 13.2 10.2 6 13.1 10.5 7 13.3 11.9 813.3 9.5 9 13.2 11.2 10  13.3 10.9 Mean Value 13.29 11.02 StandardDeviation 0.119722 0.877876

The above-indicated measurement results reveal that the mean value(13.29 NL/min.) of the flow rate of the products of the presentinvention (diaphragm valve 1 shown in FIG. 1) is greater than the meanvalue (11.02 NL/min.) of the flow rate of the products in theComparative Example by not lower than 20%. In addition, the variation(standard deviation) in the flow rate of the present invention isdrastically less than that in the Comparative Example by less than 1/7.

In the above, as the diaphragm valve 1, one having a retainer 12 isshown, but the diaphragm valve 1 may be one without having a retainer12.

INDUSTRIAL APPLICABILITY

In diaphragm valves, increasing flow rates has been desired. Thediaphragm valves in accordance with the present invention are capable ofsuppressing variation in flow rates among the diaphragm valves and arecapable of increasing the flow rates. Therefore, the present inventioncan contribute to improvement of performance of the diaphragm valves.

1. A diaphragm valve comprising: a body including a fluid inflowchannel, a fluid outflow channel, and a depression opening upward; aseat disposed demountably on a circumferential edge of the fluid inflowchannel of the body; a seat holder demountably disposed on the body tohold the seat; and a diaphragm that is pressed against and separatedfrom the seat to open and close the fluid channel, in which a fluid thathas flown into the fluid inflow channel enters the fluid outflow channelvia through holes formed in the seat holder, the diaphragm valvecharacterized in that, on a bottom surface of the depression of thebody, a seat receiving surface that receives the seat and a seat-holderreceiving surface that receives the seat holder are formed, and that inthe bottom surface of the depression of the body, an annular groove thatfaces the through holes of the seat holder is formed.
 2. The diaphragmvalve according to claim 1, wherein the seat receiving surface is flushwith the seat-holder receiving surface.
 3. The diaphragm valve accordingto claim 1, wherein, among the seat receiving surface, the seat-holderreceiving surface, and a bottom surface of the groove, the bottomsurface of the groove is formed at a lowermost level.
 4. The diaphragmvalve according to claim 2, wherein, among the seat receiving surface,the seat-holder receiving surface, and a bottom surface of the groove,the bottom surface of the groove is formed at a lowermost level.